Tapered header flow system for paper machine

ABSTRACT

Paper stock enters a tapered header at the large end and, except for a small percentage that is recirculated, is delivered to a papermaking machine through a large number of flow channels or hoses divided into two groups. The hoses of one group are connected to the header along a first row of openings, and the hoses of the second group are connected to the header along a second row of openings. The openings are spaced apart from each other both circumferentially and longitudinally of the header. The downstream ends of all the hoses lie in a single plane, and the hoses of the two groups lie respectively in surfaces curved concavely towards each other.

Waited ttes Patent [151 3,646,843 Means 1 Feb. 8, 1972 [54] TAPERED HEADER FLOW SYSTEM FOREIGN PATENTS OR APPLICATIONS FOR PAPER MACHllNE [72] Inventor: John A. Means, South Norwalk, Conn.

[73] Assignee: Time, Incorporated, Rockefeller Center,

New York, NY.

[22] Filed: Apr. 17, 1969 [21] Appl. No.: 816,894

[52] US. Cl ..162/343 [51] Int. Cl. ..D2li 1/06 [58] Field of Search ..162/300, 315, 336, 338,343

[56] References Cited UNITED STATES PATENTS 3,351,522 11/1967 Lopas 162/343 Appel ....l62/343 592,224 2/1960 Canada ..162/336 Primary Examiner-S Leon Bashore Assistant Examiner-Richard H. Anderson Attorney-Brumbaugh, Graves, Donohue & Raymond [57] ABSTRACT Paper stock enters a tapered header at the large end and, except for a small percentage that is recirculated, is delivered to a papermaking machine through a large number of flow channels or hoses divided into two groups. The hoses of one group are connected to the header along a first row of openings, and the hoses of the second group are connected to the header .along a second row of openings. The openings are spaced apart from each other both circumferentially and longitudinally of the header. The downstream ends of all the hoses lie in a single plane, and the hoses of the two groups lie respectively in surfaces curved concavely towards each other.

7 Claims, 3 Drawing Figures PATENTEO 3 I972 SHEET 1 [IF 2 I N VENI'OR. JOHN A. ME ANS his ATTORNEYS mturm w 8 2 SHEET 2 BF 2 INVENTOR. JOHN A. MEANS his ATTORNEYS TAPERED HEADER FLOW SYSTEM FOR PAPER MACHINE BACKGROUND OF THE INVENTION This invention relates to paper stock flow systems and, more particularly, to a novel and highly effective flow system including a side-entering tapered-flow header wherein the critical transition between flow into the header and flow from the header to the papermaking machine is effected in such a manner as to facilitate provision to the papermaking machine of a sheet of stock that is uniform as to basis weight and other characteristics from edge to edge.

A side-entering header is one mounted so that paper stock entering the header moves in a direction generally transverse of the machine direction in which the paper stock moves on the papermaking machine as it is formed into a paper web. The header causes the stock flow direction to deviate from the given header entry direction to a header exit direction forming an angle of about 90 with respect to the header entry direction. This is extremely difficult to effect without causing variations in a transverse direction in the characteristics of the sheet of stock supplied to the papermaking machine.

A serious and heretofore intractable problem encountered with conventional apparatus is that the flow history of stock fibers delivered to the papermaking machine is path dependent. For one thing, there is a tendency for stock flow velocity at the end of the header opposite the entrance end to be less than that at the entrance end. Even if stock velocity in the header is maintained more or less uniform in the header by tapering the header and recirculating a portion of the stock, local perturbations are caused by the very act of withdrawing stock from the header at any given location. The local perturbations at any one exit affect stock behavior at adjacent exits in ways hard to predict and even harder to compensate.

SUMMARY OF THE INVENTION An object of the invention is to remedy the deficiencies of conventional apparatus noted above. In particular, an object of the invention is to provide a method and apparatus whereby a sheet of stock of uniform characteristics from one edge to the other can be provided to a papermaking machine.

The foregoing and other objects are attained, in a representative embodiment of apparatus constructed in accordance with the invention, by the provision of a header having an upstream end of large diameter, a downstream end of small diameter through which a small portion of the stock is recirculated, and a plurality of stock delivery openings between the upstream end and the downstream end. There are also provided an undivided downstream flow channel and a plurality of flow channels in parallel with one another and collectively in series with the undivided flow channel and the header. Each of the flow channels in parallel with one another is connected at its downstream end to the undivided flow channel and at its upstream end to a separate one of the openings on the header. The header is tapered from its upstream end towards its downstream end and mounted with the downstream end at a higher elevation than the upstream end. The flow channels in parallel with one another are of equal length.

The openings on the header form two rows each extending between the upstream and the downstream end. The rows are spaced apart from each other around the circumference of the header, and planes normal to the axis of the header and passing through the openings of one of the rows alternate with planes normal to the axis of the header and passing through the openings of the other of the rows.

Alternate ones of the channels in parallel with one another and the remaining ones of such channels lie respectively in surfaces curved concavely towards each other.

This structure provides sufiicient spacing between the stock delivery openings in the header that local perturbations at any one exit have little or no effect on the behavior of stock flow at other exits. Moreover, the taper of the header and the recirculation of a portion of the stock maintain uniform stock velocity at each stock delivery exit from the header, and the curve formed by the channels in parallel with one another and the fact that such channels are all of the same length result in a history of any given small portion of stock delivered to the papermaking machine that is independent of its path through the flow system. In this way, a sheet of stock that is uniform from edge to edge is provided to the papermaking machine.

BRIEF DESCRIPTION OF THE DRAWING An understanding of additional aspects of the invention may be gained from a consideration of the following detailed description of a representative embodiment thereof, in conjunction with the accompanying figures of the drawing, wherein:

FIG. 1 is a fragmentary view in side elevation of apparatus constructed in accordance with the invention;

FIG. 2 is a view taken along the lines 2-2 of FIG, 1 and looking in the direction of the arrows; and

FIG. 3 is an assemblage of cross sections respectively taken along the lines AA, B-B, C-C, D-D, E-E, and F-F of FIG. 2 and looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT The figures show a paper stock flow system 10 constructed in accordance with the invention. The flow system 10 comprises a header 12 having an upstream end 14 of large diameter, a downstream end 16 of small diameter, and a plurality of stock delivery openings 101-186 between the downstream end 16 and the upstream end 14. For the sake of clarity, most of the openings 101-186 are omitted from the drawing.

An undivided downstream flow channel 18 is provided for delivering the stock to a papermaking machine 20 that forms the stock into a paper web. The flow channel 18 may include any suitable nozzle or slice for ejecting the stock between forming wires or permeable belts 22 and 24 respectively wound about rolls 26 and 28. The rolls 26 and 28 and the wires or belts 22 and 24 respectively rotate and move as shown by arrows 30 and 32 to receive and transport the fit of stock and form it into a paper web. The flow channel 18 is undivided in the sense that it is substantially as wide as the sheet of stock delivered to the papermaking machine, and it is possible to trace a continuous path through the channel 18 from one edge to the other in a direction generally normal to the plane of FIG. 1, all points of such path lying in the path of stock flow.

The apparatus 10 also includes a plurality of flow channels 101'186 in parallel with one another and collectively in series with the undivided flow channel 18 and the header 12. For the sake of clarity, most of the flow channels 101-186' are omitted from the drawing.

Each flow channel of the flow channels l01-186 in parallel with one another is connected at its downstream end to the undivided flow channel 18 and at its upstream end to a separate one of the openings 101-186 on the header 12.

The header 12 is tapered from its upstream end 14 towards its downstream end 16 and mounted with the downstream end 16 a higher elevation than the upstream end 14, to facilitate elimination of air bubbles through the recirculation exit. The flow channels 101-186 are of equal length.

As FIG. 2 shows, the header 12 comprises a plurality of frustoconical sections 34, 36, 38 connected in end-to-end relation. Successive sections have progressively more pronounced taper in a direction from the large-diameter end towards the small-diameter end. Thus, the section 38 has a more pronounced taper than does the section 36, which in turn has a more pronounced taper than does the section 34. In a large machine measuring several hundred inches in width, a half dozen or more sections may be provided in order to maintain the proper taper at all points along the header. The taper is such that, taking into account the withdrawal of stock along the length of the header through the openings 101-186, the velocity of stock flow in the header remains substantially constant along the length of the header. At the same time, the fabrication of the header in frustoconical sections renders the manufacturing much more convenient, rapid and economical than in the case where a complex curve must be machined in order to provide the requisite taper.

The successive sections in a direction from the large-diameter end 14 towards the small-diameter end 16 not only have more pronounced taper, but also are progressively shorter. The two factors of increasing taper and shorter lengths, plus the withdrawal of a certain proportion of the stock for recirculation, say percent of the stock delivered to the papermaking machine, combine to maintain the proper stock velocity and throughput at all points along the length of the header.

The stock delivery openings 101-186 in the header 12 are disposed in two rows 40 and 42, as FIG. 2 best shows. These rows extend between the upstream end 14 and the downstream end 16 and are spaced apart from each other around the circumference of the header by about 75 with respect to the axis 44 of the header, as FIGS. 1 and 3 best show.

The stock delivery openings 101-J86 are also spaced apart from each other longitudinally of the header 12, so that planes normal to the axis 44 of the header and passing through the stock delivery openings 101, 103, 105, etc., of the row 40 alternate with planes normal to the axis 44 of the header 12 and passing through the stock delivery openings 102, 104, 106, etc., of the row 42.

Alternate ones of the channels l01'-186' are connected respectively to the openings of one of the rows 40, 42 and the remaining ones of the channels 101186' are connected respectively to the openings of the other of the rows. Thus, the odd-numbered channels 101, 103', 105, etc., are shown as connected to the oddnumbered stock delivery openings 101, 103, 105, etc., of the row 40, while the even-numbered channels 102, 104', 106, etc., are shown as connected to the evennumbered stock delivery openings 102, 104, 106, etc., of the row 42.

The rows 40 and 42 are not straight but rather form substantially helical paths along the header 12 from the upstream end 14 to the downstream end 16. This is done in order to permit the use of hoses of equal lengths, each hose having a similar lay" when the head 12 is mounted with the small-diameter end elevated with respect to the large-diameter end,

Thus, in the section A-A of FIG. 3, the stock delivery openings 85, 86 of both rows are oriented above the horizontal plane H; in the section B-B, both openings 67, 68 are still above the horizontal, but the opening 68 of the row 42 is oriented in a direction that departs only slightly from the horizontal plane H; in the section C-C, the opening 146 in the row 42 is approximately in the horizontal plane H and extends in a horizontal direction, the opening 45 being oriented about 75 above the horizontal; in the sections DD, EE, and F--F, the openings in the row 42 are oriented below the horizontal by progressively increasing amounts, and the openings in the row 40 are oriented above the horizontal by progressively decreasing amounts. From another standpoint, successive stock delivery openings in both rows 40 and 42 are displaced in a counterclockwise direction (as seen in FIG. 3) from the upstream end to the downstream end.

Similar observations apply if the orientations of the openings are referenced to the surface S including the plane of the downstream ends of the flow channels 101-ll86 and smoothly warped to include also the axis 44 of the header 12. As FIG. 3 shows, the angle between the channel 185 at the large-diameter end 14 and the surface S is 59/2 and the angle between flow channel 186 at the large-diameter end 14 and the surface S is on the opposite side of the surface S. The corresponding angles at sections BB through F-F for the flow channels in the row 40 are, respectively, 53 a", 47 A, 43, 35 a", and 33%", while the angles for the flow channels in the row 42 at the same sections are, respectively, 21%", 27 32, 39 W, and 41%. The angles in each case total to substantially 75 between adjacent channels.

Likewise, the angle A between the horizontal and the portion of the surface S in which the downstream ends of the hoses 101186 lie equals the angle A between the vertical and a projection of the axis 44 onto the plane of FIG. 1.

The lay or curvature of the flow channels 10l'186', facilitated by the structure described above, is best shown in FIG. 1. The odd-numbered flow channels and the remaining (even-numbered) flow channels lie respectively in surfaces curved concavely towards each other. The proper lay is further facilitated by making the upstream ends of the channels of stainless steel, curved through arcs of about 37 W.

At their downstream ends, the flow channels 101-186 are oriented in the same direction and lie in the same surface S. This surface is planar at the downstream ends of the hoses 1011-186 and is shown inclined at an angle A of about 28 with respect to the horizontal, but of course the planar portion of the surface S can be horizontal, vertical, or inclined at any angle A between the horizontal and the vertical, as those skilled in the art will readily understand. In such case, the angle A is preferably varied correspondingly, so that the angles A and A are maintained equal. The hoses 101 -l 86 at their downstream ends may have different sizes and cross-sectional shapes from the sizes and shapes characterizing the remainder of the hoses, all in a manner which, per se, forms no part of the prmnt invention.

In accordance with the method of the present invention,

portions of the stock execute turns through angles of about 90 at spaced-apart points along the header 12. These are the turns by which stock flowing in the header l2 exits through the openings 101-186. In contrast to conventional methods, however, the perturbations resulting at any one of the exits 101-186 have no effect upon the behavior of the stock at other exits, including the nearest exit or exits. That is because, in accordance with the invention, the exits are spaced apart from each other both longitudinally and circumferentially, putting significantly greater separation between them than is attained in accordance with conventional apparatus and methods.

Thus there is provided in accordance with the invention novel and highly effective flow methods and apparatus whereby a sheet of stock of uniform basis weight and other characteristics from one edge to the other edge can be provided to a papermaking machine. Many modifications of the representative embodiments described above will readily occur to those skilled in the art. For example, the number of flow channels in parallel with each other can be varied in accordance with the size of the machine. The invention is to be construed as including all of the embodiments thereof within the scope of the appended claims.

I claim:

1. A paper stock flow system comprising (a) a header having an upstream entrance end of relatively large diameter, a downstream recirculation end of relatively small diameter and a plurality of separated stock delivery openings between said upstream end and said downstream end, (b) a downstream flow channel, and (c) a plurality of separated flow channels in parallel with one another and collectively in series with said downstream flow channel and said header, each flow channel of said flow channels in parallel with one another being connected at its downstream end to said downstream flow channel and at its upstream end to a separate one of said openings on said header, said header being tapered from said upstream end towards said downstream end and mounted with the highest part of said downstream end at a higher elevation than the highest part of said upstream end, and said flow channels in parallel with one another being curved and of equal length.

2. A flow system according to claim 1 wherein said header comprises a plurality of frustoconical sections connected in end-to-end relation, successive sections having progressively more pronounced taper in a direction from said relatively large-diameter end towards said relatively small-diameter end, and said openings being arranged in two rows on said header.

3. A paper stock flow system comprising (a) a header having an upstream end, a downstream end spaced apart from said upstream end along a header axis, and two rows of separated stock delivery openings each extending between said upstream end and said downstream end, (i) said rows being spaced apart from each other around the circumference of said header and (ii) planes normal to the axis of said header and respectively passing through the stock delivery openings of one of said rows alternating with planes normal to the axis of said header and respectively passing through the stock delivery openings of the other of said rows, (b) an undivided flow channel, and (c) a plurality of separated flow channels in parallel with one another and collectively in series with said undivided flow channel and said header, each flow channel of said flow channels in parallel with one another being connected at its downstream end to said undivided flow channel and at its upstream end to a separate one of said openings on said header, alternate ones of said channels in parallel with one another being connected respectively to the openings of one of said rows and the remaining ones of said channels in parallel with one another being connected respectively to the openings of the other of said rows.

4. A flow system according to claim 3 wherein said header is mounted with the highest part of said downstream end at a higher elevation than the highest part of said upstream end and said rows form substantially helical paths along said header from said upstream end to said downstream end.

5. A flow system according to claim 3 wherein said rows are angularly spaced apart from each other with respect to said 

1. A paper stock flow system comprising (a) a header having an upstream entrance end of relatively large diameter, a downstream recirculation end of relatively small diameter and a plurality of separated stock delivery openings between said upstream end and said downstream end, (b) a downstream flow channel, and (c) a plurality of separated flow channels in parallel with one another and collectively in series with said downstream flow channel and said header, each flow channel of said flow channels in parallel with one another being connected at its downstream end to said downstream flow channel and at its upstream end to a separate one of said openings on said header, said header being tapered from said upstream end towards said downstream end and mounted with the highest part of said downstream end at a higher elevation than the highest part of said upstream end, and said flow channels in parallel with one another being curved and of equal length.
 2. A flow system according to claim 1 wherein said header comprises a plurality of frustoconical sections connected in end-to-end relation, successive sections having progressively more pronounced taper in a direction from said relatively large-diameter end towards said relatively small-diameter end, and said openings being arranged in two rows on said header.
 3. A paper stock flow system comprising (a) a header having an upstream end, a downstream end spaced apart from said upstream end along a header axis, and two rows of separated stock delivery openings each extending between said upstream end and said downstream end, (i) said rows being spaced apart from each other around the circumference of said header and (ii) planes normal to the axis of said header and respectively passing through the stock delivery openings of one of said rows alternating with planes normal to the axis of said header and respectively passing through the stock delivery openings of the other of said rows, (b) an undivided flow channel, and (c) a plurality of separated flow channels in parallel with one another and collectively in series with said undivided flow channel and said header, each flow channel of said flow channels in parallel with one another being connected at its downstream end to said undivided flow channel and at its upstream end to a separate one of said openings on said header, alternate ones of said channels in parallel with one another being connected respectively to the openings of one of said rows and the remaining ones of said channels in parallel with one another being connected respectively to the openings of the other of said rows.
 4. A flow system according to claim 3 wherein said header is mounted with the highest part of said downstream end at a higher elevation than the highest part of said upstream end and said rows form substantially helical paths along said header from said upstream end to said downstream end.
 5. A flow system according to claim 3 wherein said rows are angularly spaced apart from each other with respect to said header axis by substantially 75*.
 6. A flow system according to claim 3 wherein said alternate ones of said channels in parallel with one another and said remaining ones of said channels in parallel with one another lie respectively substantially in surfaces curved concavely toWards each other.
 7. A flow system according to claim 3 wherein the downstream ends of said channels in parallel with one another are oriented in the same direction and lie substantially in a single plane. 